diff options
Diffstat (limited to 'mbr')
| -rw-r--r-- | mbr/mbr_ho.S | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/mbr/mbr_ho.S b/mbr/mbr_ho.S new file mode 100644 index 00000000..993b0c3c --- /dev/null +++ b/mbr/mbr_ho.S @@ -0,0 +1,271 @@ +/* ----------------------------------------------------------------------- + * + * Copyright 2010 Gene Cumm + * + * Portions from mbr.S: + * Copyright 2007-2009 H. Peter Anvin - All Rights Reserved + * Copyright 2009 Intel Corporation; author: H. Peter Anvin + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, + * copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom + * the Software is furnished to do so, subject to the following + * conditions: + * + * The above copyright notice and this permission notice shall + * be included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES + * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, + * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + * ----------------------------------------------------------------------- */ + +/* + * mbr_ho.S: MBR-like codeblock to display handoff data + * + * Displays the values of DL, DS, SI, the contents of [DS:SI] (16 bytes), + * the values of ES, DI then the contents of [ES:DI] (4 bytes) then reports + * a boot failure. + */ + +#define DEBUG_MARKER1 +#define DEBUG_START +#define DEBUG_LOADE +#define DEBUG_PNP + +#ifdef DEBUG_MARKER1 + .macro ASCII_MARKER1 s:vararg + .ascii \s + .endm +#else /* DEBUG_MARKER1 */ + .macro ASCII_MARKER1 s + .endm +#endif /* DEBUG_MARKER1 */ + +#ifdef DEBUG_LOADE + .macro LOADE r:req, t:req + movw (e_\r), %\t + .endm +#else /* DEBUG_LOADE */ + .macro LOADE r:req, t:req + popw %\t + .endm +#endif /* DEBUG_LOADE */ + + .code16 + .text + +entry = 0x7c00 +pnps = (entry) +pnpi = (pnps-2) +stack = (pnpi-2) +e_di = (stack-2) +e_es = (stack-4) +e_si = (stack-6) +e_ds = (stack-8) + +BIOS_page = 0x462 + + .globl _start +_start: + cli + xorw %ax, %ax + movw %ax, %ss + movw $stack, %sp + sti + cld + pushw %di /* es:di -> $PnP header */ + pushw %es + pushw %si + pushw %ds + push %cs + pop %ds + +#ifdef DEBUG_START + pushw %dx + call crlf + movw $(_start),%dx /* 0x0600 mbr.ld .text address */ + call wrhexw + call crlf +// movw $(entry - _start),%dx /* 0x7C00 */ + call caddr +caddr: popw %ax + sub $(caddr - _start), %ax + movw %ax, %dx /* Same size as pushw %ax;popw %dx */ + call wrhexw + call crlf + popw %dx +#endif /* DEBUG_START */ + + /* write DL */ +pr_dl: call wrstr + .ascii "DL: \0" + call wrhexb + /* DS */ +pr_ds: call wrstr + .ascii " DS: \0" +// popw %dx + LOADE ds, dx + pushw %dx + popw %es + call wrhexw + /* SI */ +pr_si: call wrstr + .ascii " SI: \0" +// popw %dx + LOADE si, dx + pushw %dx + popw %di + call wrhexw + call crlf + /* DS:SI */ + movw $16, %cx + call wrhexbses + call crlf + + /* ES */ +pr_es: call wrstr + .ascii "ES: \0" +// popw %dx + LOADE es, dx + pushw %dx + popw %es + call wrhexw +pr_di: call wrstr + .ascii " DI: \0" +// popw %dx + LOADE di, dx + pushw %dx + popw %di + call wrhexw + call crlf + /* ES:DI */ /* %es:0(%di) */ + movw $4, %cx + call wrhexbses + call crlf + + /* $PnP Scan */ + movw $0xf000, %dx + pushw %dx + popw %es + movw $0, %si + movw $0x1000, %cx + /* 0x506E5024 */ + movw $0x5024, %dx + movw $0x506E, %bx +ch_pnp: es lodsw + cmp %dx, %ax + jne ch_pnp_l + es lodsw + cmp %bx, %ax + je pr_pnp +ch_pnp_l: + addw $14, %si + andw $0xFFF0, %si + loopw ch_pnp + jmp end +pr_pnp: + call wrstr + .ascii "$PnP-\0" + movw %es, %dx + call wrhexw + movb $':, %al + call wrchr + movw %si, %dx + andw $0xFFF0, %dx + call wrhexw + call crlf + +end: + jmp bootfail + + ASCII_MARKER1 "wc" +wrchr: + movb $0x0e, %ah + movb (BIOS_page), %bh + movb $0x07, %bl + int $0x10 /* May destroy %bp */ + ret + + ASCII_MARKER1 "ws" +wrstr: + pop %si +wrstr_l: + lodsb + cmpb $0, %al + je wrstr_d + call wrchr + jmp wrstr_l +wrstr_d: + push %si + ret + +crlf: + call wrstr + .ascii "\r\n\0" + ret + + ASCII_MARKER1 "hx" +wrhexn: + and $0x0F, %al + cmpb $10, %al + jae .alph + addb $'0, %al + jmp .wc +.alph: + addb $('A - 10), %al +.wc: + call wrchr + ret + +wrhexb: + movb %dl, %al + pushw %ax + rorw $4, %ax + call wrhexn + popw %ax + call wrhexn + ret + +wrhexw: + rorw $8, %dx + call wrhexb + rorw $8, %dx + call wrhexb + ret + + ASCII_MARKER1 "HE" +wrhexbses: + pushw %di + popw %si +wrhexbses_l: + movb $' , %al + call wrchr + es lodsb + movw %ax, %dx + call wrhexb + loop wrhexbses_l + ret + +data: + ASCII_MARKER1 "bf" +bootfail: + int $0x18 /* Boot failure */ +die: + hlt + jmp die + +zerob: /* Begin zeroing block to fill to desired length */ + /* 420 bytes for FAT32 */ +zeroln = (420 - (zerob - _start)) + .=.+zeroln /* prevents overflow */ +zeroe: |